Size dependent free vibration analysis of functionally graded piezoelectric micro/nano shell based on modified couple stress theory with considering thickness stretching effect

Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform temperature rising. Size dependency is included in governing equations based on the modified couple stress theory. Hamilton's principle is used to derive governing equations of the cylindrical micro/nano shell. Solution procedure is developed using Navier technique for simply-supported boundary conditions. The numerical results are presented to investigate the effect of significant parameters such as some dimensionless geometric parameters, material properties, applied voltages and temperature rising on the free vibration responses.     

Fullerene bisadduct stabilizers: The effect of different addition positions on inhibiting the autocatalytic decomposition of nitrocellulose absorbed nitroglycerin

To explore the effect of different positions and number of pyrrolidine bound to the carbon cage on the stabilization effect of fulleropyrrolidine derivatives to nitrocellulose (NC)/nitroglycerine (NG), we synthesized N-(4-methoxy) phenylpyrrolidine-C₆₀ and four different of bis(N-(4-methoxy) phenylpyrrolidine)-C₆₀ compounds through Prato reaction. Their structures were characterized by UV–vis, ¹H NMR, ¹³C NMR, high-resolution mass spectroscopy, and single-crystal X-ray diffraction. Their stabilization effect to NC/NG were investigated using differential scanning calorimetry, methyl violet, vacuum stabilization effect, weight loss, and accelerating rate calorimeter tests. The results indicated these compounds had excellent stabilization effect to NC/NG. The stabilization effect of the fulleropyrrolidine bisadducts to NC/NG is significantly better than that of fulleropyrrolidine monoadduct and C₆₀. Moreover, the position where pyrrolidine binds to fullerene in fulleropyrrolidine bisadducts is different, and its stabilization effect to NC is also different. The stabilization effect order of different bisadduct isomers to nitrocellulose is as follows: e-edge > trans-2> cis-2> trans-3. Electron paramagnetic resonance (EPR) and FT-IR were used to study the stabilization mechanism of fulleropyrrolidine derivatives to NC/NG. The EPR results also show that fulleropyrrolidine bisadducts with different addition sites have different abilities to absorb nitroxide, and their ability is better than that of the monoadduct and C₆₀, which is consistent with the results of stabilization effect performance test.     

次声波技术与心理战应用

次声波是一种频率变化范围在10?4 Hz～20 Hz之间的声波,它具有穿透力强、传输距离远以及不易被吸收的特点,以此制造的次声波武器伤人但不毁物。近年来,随着高新技术的不断发展,次声波武器在心理战领域得到了广泛应用。本文首先对次声波技术及次声波武器的概念进行了简要介绍;其次,研究了次声波的生物学效应,分析了次声波频率、声压强度以及作用时间与生物学效应的关系,发现三种次声波的作用参数与生物学效应之间的关系虽然错综复杂,但也有一定规律可循;最后,提出了次声波武器在心理战的三个潜在应用前景,即利用次声波穿透力强的特点发展对掩体人员作战的心理战装备、利用次声波的生物学效应发展反恐作战的心理战装备以及利用次声波的生理致伤机理发展心理战防护装备。     

Starfabric系统拓扑结构及系统性能关系分析

Starfabric是一种新型总线,基于Starfabric构建的网络系统具有高带宽、可扩展性好、拓扑结构构建灵活等优点。Starfabric通信性能具有不同于传统网络的特殊性,有效规划网络的拓扑结构对网络性能有很大的影响。文章结合对传统网络拓扑结构和对Starfabric通讯性能的分析,深入研究Starfabric系统拓扑结构和系统通讯性能的关系,归纳出构建Starfabric系统时应该遵循的规则和系统有效带宽的公式,使得系统拓扑结构得以优化,以提高系统的整体通讯效能。     

基于可拓工程方法的舰空导弹作战通道性能分析

分析了舰空导弹作战通道性能的影响因素,应用可拓工程方法建立了舰空导弹作战通道性能多指标参数的物元可拓评估模型,以定量的结果对舰空导弹作战通道性能进行了评估分级,并与层次分析法的结果进行了比较,结论基本一致。为舰空导弹作战通道性能评估问题寻求出一种新方法,其评估结果可为决策提供定量依据。     

无线电引信超宽带电磁脉冲效应研究

利用超宽带(UWB)电磁脉冲发生器对不同姿态的某型无线电引信进行了超宽带电磁脉冲辐照实验研究。实验表明:电点火头本身在UWB辐照下是安全的,当超宽带电磁脉冲峰峰值场强达到106 kV/m时,在引信加电工作情况下可以使实验引信全部引爆;此外,引信-弹体自身等效天线长度增加会导致无线电引信超宽带电磁脉冲效应更加明显。     

几种气相缓蚀剂组分间协同作用研究

采用气相防锈甄别实验及量子化学计算方法对钼酸铵、亚硝酸钠、苯甲酸、苯甲酸钠、肉桂酸和肉桂酸钠等6种气相缓蚀剂的气相防锈能力和组分之间的协同作用进行研究．结果表明,4种单组分盐类物质本身不具备气相防锈能力,但2种无机盐和2种有机盐之间具有良好的协同效应．从防锈效果上看,钼酸铵完全可以代替亚硝酸钠,但由于其用量较高,成本上会高于传统的亚硝酸钠系气相缓蚀剂．     

基于灰色关联分析的反导导弹战斗部作战效能评估

针对反导导弹战斗部的性能特点,以灰色关联理论为基础,采用灰色加权关联度分析进行综合评判,建立了反导导弹战斗部作战效能评估模型．最后通过算例,验证了该模型的完整性,最终为决策者做出合理的作战决策提供了理论参考．     

基于体系结构方法的机群对海作战活动分析

机群综合电子信息系统在高技术局部战争环境中可以为机群协同作战提供信息能力与优势,对机群作战活动的分析是设计其体系结构的基础,因此对机群在作战中的活动进行分析有重要意义。针对海军航空兵机群的对海作战,利用体系结构设计工具,在DoD AF V1.0框架下分析了机群对海作战活动,并在此基础上开发了相关作战视图。     

网络中心与平台中心的声纳浮标探测概率建模

针对基于网络中心与平台中心的声纳浮标组网探测问题,在分析声纳浮标瞥概率模型的基础上,建立了两种方式下声纳浮标网的发现概率计算模型,给出了评价声纳浮标网探测效能指标.最后以声纳浮标拦截阵探测为例,对基于网络中心和基于平台中心的声纳浮标网探测效能进行分析,仿真了声纳浮标布设数量与布设间距对探测效能的影响.结果表明:当声纳浮标布设数量超过一定值时,继续增加并不能使网络中心的探测效能显著增加;与平台中心探测相比,声纳浮标瞥概率为Fermi模型时,网络中心探测的优势并不显著.